The increasing demand of integrating electronic devices onto automotive, industrial, and consumer platforms requires more sophisticated power conversion and distribution designs. Often these electronic devices include embedded processors, memories, and other electronic components that are operated from one battery source. DC-to-DC voltage converters are used to supply different voltages to the different electronic components.
Switching DC-to-DC voltage converters are popular because of their high efficiency over a wide voltage input range. In contemporary low-power switching DC-to-DC converters, voltage regulation is achieved by pulse-width modulation (PWM). In pulse-width modulation, a control circuit produces a rectangular pulse wave that drives an internal transistor (or transistors in a synchronous device), rapidly switching the transistor(s) at a set frequency, typically in the range of a few megahertz. The output voltage of such a DC-to-DC voltage converter is proportional to the duty cycle of the drive pulse. A voltage- or current-feedback control loop allows the PWM controller output to regulate the output voltage in response to load changes.
Components such as central processing units (CPUs), memory modules, and application-specific integrated circuits (ASICs) require power supplies that maintain a tightly regulated output voltage under fast high-current transient conditions. To achieve this regulation, many DC-to-DC converters incorporate a very large output capacitance. However, incorporating such a large output capacitance is costly and limits power density.